import java.util.stream.IntStream;

public class Manage4 {
    private static int id = 0;

    private Manage4() {
        id++;
    }

    private static class Manage4Holder {
        private final static Manage4 INSTANCE = new Manage4();
    }

    public static Manage4 getInstance() {
        return Manage4Holder.INSTANCE;
    }

    @Override
    public String toString() {
        return "id=" + id;
    }

    public static void main(String[] args) {
        IntStream.range(0, 100).forEach(i -> new Thread(() -> {
            System.out.println(Manage4.getInstance().hashCode());
        }
        ).start());
    }
}
